wip refactoring: better logging and error systems

internal/app/api/pkg/handler/merge.go

@@ -0,0 +1,24 @@
+package handler
+
+import (
+	"github.com/labstack/echo/v4"
+	"github.com/thecodingmachine/gotenberg/internal/app/api/pkg/context"
+	"github.com/thecodingmachine/gotenberg/internal/pkg/printer"
+)
+
+// Merge is the endpoint for
+// merging PDF files.
+func Merge(c echo.Context) error {
+	ctx := context.MustCastFromEchoContext(c)
+	r := ctx.Resource()
+	opts, err := r.MergePrinterOptions()
+	if err != nil {
+		return err
+	}
+	fpaths, err := r.Fpaths(".pdf")
+	if err != nil {
+		return err
+	}
+	p := printer.NewMerge(fpaths, opts)
+	return convert(ctx, p)
+}